The present disclosure relates to voltage detection circuits utilized in power-on reset of, for example, semiconductor devices.
A reference voltage generated from a power supply voltage needs to be stable to normally operate an electronic circuit including a comparator, which receives the reference voltage as one of the inputs to be compared. However, when a power supply is turned on, the power supply voltage is low, thereby making the reference voltage unstable. To address this problem, a voltage detection circuit is practically used, which outputs an enable signal indicating whether or not a required reference voltage is obtained.
In order to detect rising of the output of a reference voltage supply or rising of the output of a reference current supply, conventional art include, between a power supply and ground, a first series circuit including a resistive element, a diode, and an N-channel MOS transistor in parallel to a second series circuit including a P-channel MOS transistor and a resistive element. A voltage at the coupling point between the resistive element and the diode is applied to the gate of the P-channel MOS transistor. A reference voltage or a reference current is used to control the operation of the N-channel MOS transistor. See, for example, Japanese Unexamined Patent Publication No. 2010-223796.